Diabetes is the third leading cause of death in African Americans. A significant proportion of the increased mortality is due to cardiovascular disease. The investigators propose to evaluate the efficacy of thallium scintigraphy as a means of early detection of coronary artery disease (CAD), and propose to test its reliability in diabetic patients with minimal or absent symptoms. A cohort of diabetic and non-diabetic patients with similar other risk factors will have baseline myocardial scintigraphy. Patients with abnormal studies suggestive of CAD will be referred for cardiac catheterization. Coronary angiography will be compared to the perfusion results to assess the specificity of this technique in detecting CAD in diabetic as compared to control subjects. Patients with poor diabetic control will receive a three-month period of intensive efforts to achieve euglycemia followed by frequent evaluations in order to maintain the improved diabetic control. Data collected from follow-up thallium scintigraphy will allow assessment of the contribution of poor metabolic control to abnormal myocardial perfusion. All patients will be receiving monthly clinical evaluations followed by quarterly evaluations to record the onset of progression of cardiac symptoms. The thallium scintigram will be repeated annually.